In a typical security system, a main controller communicates with sensors positioned throughout a surveillance area, such as a home or business, to monitor various security conditions. For purposes of immunity from attack, the main controller forms a control panel that often is housed in a heavy, metal box. The control panel is typically placed in a remote location in the surveillance area such as in a basement or utility closet. The housing provides some degree of protection against an intruder trying to disable the internal circuitry for the main controller.
The sensors placed throughout the surveillance area may include door/window sensors, passive infrared sensors for motion, temperature sensors, and the like. Each sensor includes a transmitter. When a change in condition is sensed, the transmitter associated with a sensor transmits a sensor signal. The sensor signal includes information conveying the change in condition to the main controller. The sensor signal also can be transmitted to the main controller by hardwired communication. The various sensors are assigned zone numbers present in the main controller according to specific conditioning requirements.
The security system also includes a keypad or other user input device that is placed remotely from the control panel associated with the main controller. The keypad typically is placed or located near the entrance door for the house. This keypad may communicate with the main controller by hardwired or wireless communication. In some cases, the keypad may take the form of a portable, wireless unit that is carried by the resident, e.g., on a keychain.
When the resident opens a door that is monitored by a door/window sensor, the sensor transmits a sensor signal to the main controller indicating that the door has been opened. At that time, the main controller initiates a timer, giving the homeowner a delay period in which the security system can be disarmed using the keypad that is near the door. The delay period is usually referred to as the entry delay. If the security system is not disarmed within the entry delay, e.g., thirty seconds, the main controller enters an alarm state and generates an alarm signal. In response to the alarm condition, the security system may sound an alarm. Also, the main controller may be tied to a telephone system for the purpose of notifying a security agency or police of the alarm condition.
In the event an intruder enters the home and attempts to disable the security system, he is faced with two levels of difficulty. First, the main controller is located remotely from the main entrance and keypad. Indeed, the main controller often will be difficult to locate within the entry delay. Also, the intruder may misdirect his efforts toward the hardwired keypad next to the door, which will have no effect on the function of the remote control panel. Second, the housing containing the main controller will slow the intruder's efforts to access the internal electronics, particularly if the housing is formed from heavy metal. Thus, in a typical security system, it is generally difficult for an intruder to circumvent the system by disabling the main controller.
In security systems used for a building complex having multiple units, however, the task of disabling the main controller often is less daunting for an intruder. Unlike singlehome security systems, a multiple-unit system typically includes a local, unit security system for each unit. An apartment or condominium complex, for example, may provide a unit security system for each residential unit. An office building complex similarly may provide a unit security system for each office suite. Other commercial building complexes may include a unit security system for commercial units such as businesses or storage facilities.
The local security system includes a unit controller and a keypad or other user input device. Due to space and cost limitations, however, the unit controller and keypad typically are physically integrated with one another in a common control panel. For ready access to the keypad by the resident, the integrated control panel is installed near the main door to the unit. Each unit security system has one or more sensors to monitor, for example, the front door and any accessible windows. In some cases, motion sensors also may be provided. As in a single-home system, the sensors communicate with the unit controller by hardwired or wireless communication.
Instead of a link to a main controller, each unit controller has a direct telephone link to a remote security agency or police. In the event a unit controller indicates an alarm condition, it uses the telephone connection for notification. Connection of each unit controller to the telephone system is quite costly in terms of installation. For example, each unit controller must be equipped with an RJ3 IX line seizure device in order to take control of the telephone line for communication purposes. The line seizure device must be connected between the incoming telephone line and the first telephone in the unit that connects to the line. As a result, significant installation time is consumed by efforts to locate and obtain access to the proper telephone line location within the unit. Also, seizure of the telephone line by the security system can tie up the local telephone line for the unit, particularly in an emergency situation. As a further concern, reliance on a telephone line makes the system dependent on telephone service. Because telephone service is typically disconnected when the unit is vacant, unit vacancy renders the system inoperable and the unit particularly vulnerable to intrusion.
The physical integration and accessible location of the unit controller and keypad also makes multiple-unit security systems more susceptible to disablement by intruders. Specifically, intruders can disable the unit controller by essentially smashing the common control panel upon entry into the unit. When the intruder enters the unit through the main door, an associated sensor communicates a sensor signal to the unit controller. In response, the unit controller initiates a delay timer for the entry delay to allow a resident time to disable the security system. With its convenient location, however, an intruder has sufficient time to smash the control panel before expiration of the entry delay. As a result, the unit controller can be disabled before an alarm signal is sent via the telephone line. In other words, the unit security system can be rendered inoperable by an intruder before the alarm is activated.